Sheet conveying device and image forming apparatus incorporating the sheet conveying device

Abstract

A sheet conveying device includes a pair of rollers including a first roller and a second roller to hold a sheet conveyed between the first and second rollers; a biasing member to bias the first roller toward the second roller; a biasing force changer to change a biasing force of the biasing member; control circuitry to, when a predetermined changing condition is met, cause the changer to change the biasing force and cause the rollers to convey the sheet; an operation detector to detect a changing operation of the changer; and a notification device to notify an abnormality of the changing operation when the operation detector detects the abnormality. When the operation detector detects the abnormality, the control circuitry performs sheet conveyance control to cause the rollers to convey the sheet without causing the changer to change the biasing force, regardless of whether the predetermined changing condition is met.

The invention claimed is: 
     
       1. A sheet conveying device, comprising:
 a pair of rollers including a first roller and a second roller configured to hold a sheet conveyed between the first roller and the second roller; 
 a biasing member configured to bias the first roller toward the second roller; 
 a biasing force changer configured to change a biasing force of the biasing member between at least a first biasing force and a second biasing force; 
 control circuitry configured to, in response to a desired changing condition being met, cause the biasing force changer to change the biasing force and cause the pair of rollers to convey the sheet; 
 an operation detector configured to detect whether a changing operation of changing the biasing force of the biasing force changer between at least the first biasing force and the second biasing force has been performed, and detect an abnormality of the changing operation in response to the changing operation not being performed; and 
 the control circuitry being further configured to, in response to the operation detector detecting the abnormality of the changing operation has occurred, perform sheet conveyance control to cause the pair of rollers to convey the sheet without causing the biasing force changer to change the biasing force, regardless of whether the desired changing condition is met. 
 
     
     
       2. The sheet conveying device according to  claim 1 , wherein the control circuitry is further configured to determine whether the desired changing condition is met according to a type of the sheet. 
     
     
       3. The sheet conveying device according to  claim 2 ,
 wherein the type of the sheet includes a type relating to different thicknesses of sheets. 
 
     
     
       4. The sheet conveying device according to  claim 3 ,
 wherein the biasing force changer is configured to change the biasing force so that the biasing force increases as a thickness of the sheet increases. 
 
     
     
       5. The sheet conveying device according to  claim 1 , wherein the control circuitry is further configured to:
 perform the sheet conveyance control in response to the operation detector detecting the abnormality of the changing operation has occurred in response to the biasing force being changed by the biasing force changer to perform sheet conveyance by the pair of rollers. 
 
     
     
       6. The sheet conveying device according to  claim 1 , wherein the control circuitry is further configured to:
 perform a confirmation operation of confirming whether the operation detector detects the abnormality of the changing operation has occurred before the pair of rollers convey the sheet; and 
 perform the sheet conveyance control in response to the operation detector detecting the abnormality of the changing operation has occurred in the confirmation operation. 
 
     
     
       7. The sheet conveying device according to  claim 1 , further comprising:
 a sheet feeding member upstream from the pair of rollers in a direction of conveyance of the sheet, the sheet feeding member being configured to convey the sheet; and 
 the control circuitry is further configured to change the biasing force based on an operation start timing of the sheet feeding member to convey the sheet. 
 
     
     
       8. The sheet conveying device according to  claim 1 , further comprising
 a sheet detector upstream from the pair of rollers in a direction of conveyance of the sheet; and 
 the control circuitry is further configured to change the biasing force based on a detection timing at which the sheet detector detects the sheet being conveyed. 
 
     
     
       9. The sheet conveying device according to  claim 1 , further comprising:
 a pressing portion configured to press the biasing member toward the second roller, the pressing portion being rotatable; 
 a sensor configured to change an output signal in accordance with the rotation of the pressing portion; and 
 the operation detector is further configured to detect an abnormality of the changing operation has occurred in response to the output signal of the sensor not changing within a desired period of time after the control circuitry causes the pressing portion to rotate. 
 
     
     
       10. An image forming apparatus, comprising:
 a sheet conveying device comprising,
 a pair of rollers including a first roller and a second roller configured to hold a sheet conveyed between the first roller and the second roller, 
 a biasing member configured to bias the first roller toward the second roller, 
 a biasing force changer configured to change a biasing force of the biasing member between at least a first biasing force and second biasing force, 
 control circuitry configured to, in response to a desired changing condition being met, cause the biasing force changer to change the biasing force and cause the pair of rollers to convey the sheet, 
 an operation detector configured to detect whether a changing operation of changing the biasing force of the biasing force changer between at least the first basing force and the second biasing force has been performed, and detect an abnormality of the changing operation has occurred in response to the changing operation not being performed, and 
 the control circuitry being further configured to, in response to the operation detector detecting the abnormality of the changing operation has occurred, perform sheet conveyance control to cause the pair of rollers to convey the sheet without causing the biasing force changer to change the biasing force, regardless of whether the desired changing condition is met; and 
 
 an image forming device configured to form an image on the sheet conveyed by the sheet conveying device. 
 
     
     
       11. The image forming apparatus according to  claim 10 , further comprising:
 a plurality of sheet conveyance passages including a first sheet conveyance passage and a second sheet conveyance passage; and 
 a movable member, 
 wherein the pair of rollers of the sheet conveying device are configured to hold a sheet conveyed through the first sheet conveyance passage, and 
 wherein the biasing force changer is further configured to change the biasing force of the biasing member in conjunction with an operation of the movable member that operates in response to the sheet being conveyed through the second sheet conveyance passage. 
 
     
     
       12. The image forming apparatus according to  claim 11 , wherein the second sheet conveyance passage is a bypass sheet conveyance passage configured for manual feeding. 
     
     
       13. A sheet conveying device, comprising:
 a pair of rollers including a first roller and a second roller configured to hold a sheet conveyed between the first roller and the second roller; 
 a biasing member configured to bias the first roller toward the second roller; 
 a biasing force changer configured to change a biasing force of the biasing member between at least a first biasing force and a second biasing force; 
 control circuitry configured to, in response to a desired changing condition being met, cause the biasing force changer to change the biasing force and cause the pair of rollers to convey the sheet; 
 an operation detector configured to detect whether a changing operation of changing the biasing force of the biasing force changer between at least the first biasing force and the second biasing force has been performed, and detect an abnormality of the changing operation has occurred in response to the changing operation not being performed; and 
 the control circuitry being further configured to, in response to the operation detector detecting the abnormality of the changing operation has occurred, perform sheet conveyance control to cause the pair of rollers to convey the sheet without causing the biasing force changer to change the biasing force, regardless of whether the desired changing condition is met, 
 wherein the biasing force changer is further configured to change the biasing force so that the biasing force increases as a thickness of the sheet increases. 
 
     
     
       14. The sheet conveying device according to  claim 13 , further comprising:
 a pressing portion configured to press the biasing member toward the second roller, the pressing portion being rotatable; 
 a sensor configured to change an output signal in accordance with the rotation of the pressing portion; and 
 the operation detector is further configured to detect the abnormality of the changing operation has occurred in response to the output signal of the sensor not changing within a desired period of time after the control circuitry causes the pressing portion to rotate. 
 
     
     
       15. The sheet conveying device according to  claim 13 , wherein the control circuitry is further configured to determine whether the desired changing condition is met according to a type of the sheet. 
     
     
       16. The sheet conveying device according to  claim 15 ,
 wherein the type of the sheet includes a type relating to different thicknesses of sheets. 
 
     
     
       17. The sheet conveying device according to  claim 16 ,
 wherein the biasing force changer is configured to change the biasing force so that the biasing force increases as a thickness of the sheet increases. 
 
     
     
       18. The sheet conveying device according to  claim 13 , wherein the control circuitry is further configured to:
 perform the sheet conveyance control in response to the operation detector detecting the abnormality of the changing operation has occurred in response to the biasing force being changed by the biasing force changer to perform sheet conveyance by the pair of rollers. 
 
     
     
       19. The sheet conveying device according to  claim 13 , wherein the control circuitry is further configured to:
 perform a confirmation operation of confirming whether the operation detector detects the abnormality of the changing operation has occurred before the pair of rollers convey the sheet; and 
 perform the sheet conveyance control in response to the operation detector detecting the abnormality of the changing operation has occurred in the confirmation operation. 
 
     
     
       20. The sheet conveying device according to  claim 13 , further comprising:
 a sheet feeding member upstream from the pair of rollers in a direction of conveyance of the sheet, the sheet feeding member being configured to convey the sheet; and 
 the control circuitry is further configured to change the biasing force based on an operation start timing of the sheet feeding member to convey the sheet.